First of all, only three countries are allowed to enter Bhutan without a visa, those are:

India

Bangladesh

Maldives

Indian Nationals visiting Bhutan need one of the following Travel Documents:

Valid Indian Passport with a 6 months validity

Voter Identity Card issued by the Election Commission of India

Once you have any of these, proceed to the Regional Immigration Office, Royal Government of Bhutan in Phuentsholing to obtain your Entry Permit.

For Indian Nationals who don't have any of these or are travelling to Bhutan by land, you can opt to apply for an Identification Slip. The process is as follows:

1. Once you arrive at the Phuentsholing border, go to the Consulate General of India in Phuentsholing. Make sure that your wife has two passport sized photographs. Then, she must have any two of the following documents:

2. Fill up the application form which can be downloaded online for the Identification Slip. Submit the two passport sized photographs, the completed Identification Slip form and any two of the documents above and wait for the Identification Slip.

Once you have received the Identification Slip, proceed to the Regional Immigration Office, Royal Government of Bhutan in Phuentsholing to obtain your Entry Permit.

When both of you guys have received your Entry Permit, you can then visit Thimphu and Paro. Other areas are restricted and you would need a special permit to visit them.

The Consulate General of India in Phuentsholing and the Regional Immigration Office are open from Monday to Friday except public holidays.

Once you guys have your Entry Permit, you're only allowed to visit two places in Bhutan: Thimphu and Paro.

Thimphu is the capital of Bhutan, it was just declared in the year 1961. It isn't as developed as other capitals so you might get surprised once you get there. However, it is slowly developing, just recently, a new stadium and a river side park was opened in the city. Aside from that, you're still going to see ancient structures in the city itself. One unique feature of this city is that it doesn't have traffic lights on the streets. Some attractions here are:

Lhakhangs/Gompas

Changangkha Lhakhang - It was Lam Phajo Dugom Zhigpo who built this temple. There's a statue here of Avaloketesvara, the Buddha of compassion, in his manifestation of 11 heads and 1,000 hands and eyes. It is built with bronze and plated with gold. Children born in the region are taken into this temple as this is considered their spiritual home.

Zangtho Pelri Lhakhang - The name Zangtho Pelri means abode of Guru Rinpoche. It was Dasho Aku Thongmi who built this temple. Inside, you'll find several statues of Guru Rinpoche.

National Memorial Chorten - This chorten was built in the memory of the third king of Bhutan, Jigme Dorji Wangchuck. You'll find statues and paintings inside about Buddhist principles.

Kuensel Phodrang or Buddha Dordenma Statue - This is one of the biggest statues of Buddha in the world. It measures about 51.5 metres in height and is made of bronze. About 125,000 smaller statues of Buddha are around the Buddha Dordenma.

Museums

National Folk Heritage Museum - This was built in the 19th Century and contains artefacts showcasing the rural life of the people in the region. Some of the items here are millstones, hot stone bath and kitchen gardens.

National Textile Museum - This was established in 2001 by Ashi Sangay Choden Wangchuck. This museum showcases the Bhutanese textiles, royal attires and even crowns of the royal family. Tourists can also watch the local weaving process in here.

Alaya Gallery - This is run by Voluntary Artists Studio Thimpu (VAST), a group of professional artists in Bhutan aiming to preserve the art and culture of the region. You can see different painting exhibitions here every week.

Water Dragon Gallery - This is run by Pema Tshering and showcases artworks depicting everyday Bhutanese life. There are also some books and documentaries you can purchase in here.

Parks

Royal Botanical Garden - This was built in the year 1999 under the National Biodiversity Centre and the Ministry of Agriculture and Forests. There are about 10,000 species of plants in here. The orchids here have over 200 species already.

Motithang Takin Preserve - This is a wildlife reserve for the national animal of Bhutan, the Takin. The Bhutan Takin is native to Bhutan, India, Tibet and China. Taxonomists are uncertain of the phylogeny of this animal and sometimes classify it as an antelope-goat.

Coronation Park - This was built to honour the King Ashi Chimi Yangzom Wangchuck. You can find swings, slides, a miniature basketball court and a small sand football ground here.

Landmarks

Tashichho Dzong - It was Lama Gyalwa Lhanangpa who built this dzong. In 1641 though, Zhabdrung Ngawang Namgyal built a large one called the Lower Dzong. When a fire destroyed the original dzong, they moved everything to the Lower Dzong. Since 1952 though, the Tashichho Dzong became the seat of the government.

Simtokha Dzong - The name Simtokha means "Atop a Demon" as the dzong was built to remove the evil spirits in the area. There's a statue of Yeshay Gonpo, the presiding deity of Bhutan, inside the dzong.

Others

Centenary Farmers Weekend Market - This is open only from Friday afternoons until Sunday. It's a great place to see the goods and produce of Bhutan. Aside from that, there's a few stalls, across the footbridge, selling some handicrafts and textiles.

National Institute of Traditional Medicine - This is a training centre for medical practitioners. This is also a place where production of herbal medicines are done.

National Library of Bhutan - The world's largest book, entitled "Bhutan" can be found in this library. Along with that, you can find books hundreds of years old already in this library.

Now, let's go to Paro, which is a valley rich in history and culture. If you love nature and heritage, then you must visit Paro. This is also where the only airport in Bhutan is located. Some attractions here are:

Lhakhangs

Taktsang Monastery - This monastery can be found off the side of a cliff, at about 900 metres above the Paro Valley. Another name for this is the "Tiger's Nest," named so because the Guru Rinpoche arrived here on the back of a tigress.

Kichu Lhakhang - This has two temples: one built by Songtsen Gampo and the other built by H.M. Ashi Kesang. It is said to have been built as far back as the 7th Century.

Jangsarbu Lhakhang - There's a statue of Sakyamuni Buddha here. Some say that the statue was supposed to be transferred to the Paro Dzong, however when they were trying to move it, they weren't able to lift the statue. So it was decided that the statue would stay in the temple.

Landmarks

Rinpung Dzong - This was built by Shabdrung Ngawang Namgyal. This is the place of office of the Monastic Body of Paro, the District Administrative Head of Dzongda and the Thrimpon of Paro.

Drukgyel Dzong - This was built by Shabdrung Ngawang Namgyal to commemorate his victory against the Tibetan invaders. Just below the dzong, you can have a great view of the Mount Chomolhari.

Museum

National Museum of Bhutan - Its location is in a former watchtower. Here you can find artefacts about the history of Bhutan.

Adventure

Chele La Pass - This is about 3,988 metres above sea level and is considered as the highest point in Bhutan. At its peak, you can see the Jomolhari and Jichu Drake mountains. You're also sure to find a variety of flowers at the top, like rhododendrons and wild roses.

I've heard that if you want to visit Bhutan and you're from the States (like I am), you have to have a passport AND a visa which is more difficult to acquire. Bhutan is more "closed off" to people from the States (as well as other countries that have stringent requirements for American entry.) We have no problem with Bhutan (nor do they have a problem with us), that's just their law for Americans entering their country. (And what a beautiful country it is!)